1. Field of the Invention
The present invention relates to a method and apparatus which enables deep-sky objects to be found by using as a reference only the bright, easily recognizable, stars of 3rd magnitude or brighter. The method can advantageously be implemented on telescopes using an alt-azimuth mounting system, commonly known as a Dobsonian mounting.
2. Related Art
Finding deep-sky objects can be a difficult and frustrating task for beginners in amateur astronomy (also called "backyard astronomy"), especially in the light polluted skies that exist around our major cities. The known way, in backyard astronomy, to find deep-sky objects in the sky, when using an alt-azimuth mounted telescope, is to use the bright, easily visible, stars as a guide. However, the number of easily visible stars, i.e. brighter than 3rd magnitude, is relatively limited and it is very hard to move the telescope several degrees (e.g. 15 degrees) from one star and several degrees (e.g. 17 degrees) from another in order to locate a deep-sky object.
Initially a novice amateur astronomer begins by learning some of the major constellations and bright star names in the sky. Following this, the next challenge is typically to search out some of the brighter deep-sky objects. Charles Messier in the late 18th century compiled a list of 110 deep-sky objects which still represents the initial observing challenge for most amateur astronomers. Each of the 110 deep-sky objects is designated by M1, M2, M3, etc.
For example, M67, an open cluster in Cancer (see FIG. 1) is located 19.0 degrees from Procyon and 18.8 degrees from Regulus and there are no bright stars in between. It is hard to locate M67 if the sky has a limiting naked eye magnitude of 3.5, which is often the case for backyard astronomy.